The present application relates to a piezoelectric device used in a piezoelectric sensor, a piezoelectric actuator, and a pyroelectric infrared ray sensor, an angular velocity sensor including the piezoelectric device, and a method of manufacturing a piezoelectric device.
From the past, lead zirconium titanate (Pb1+X(ZrYT1−Y)O3+X) (hereinafter, referred to as PZT) is used as a piezoelectric material of a piezoelectric thin film used for a piezoelectric sensor such as an angular velocity sensor, an ink jet head, and the like. Various techniques are proposed for improving piezoelectric characteristics, ferromagnetic material characteristics, pyroelectric characteristics, and the like of the PZT (see, for example, Japanese Patent Application Laid-open No. Hei 06-350154 (paragraphs (0030) to (0044), (0060) to (0073), FIGS. 3, 4, etc.) and Japanese Patent Application Laid-open No. Hei 09-298324 (paragraphs (0007) to (0009), FIG. 5); hereinafter, will respectively be referred to as Patent Document 1 and Patent Document 2).
Patent Document 1 discloses a PZT thin film whose crystalline structure is rhombohedral, in which, when lead zirconium titanate is represented by Pb1+Y(ZrXT1−X)O3+Y, a PbO excessive composition ratio Y is within a range of 0≦Y≦0.5, and a Zr composition ratio X is within a range of 0≦Y≦0.55. The PZT thin film of Patent Document 1 exhibits favorable piezoelectric characteristics. Moreover, there is also disclosed a PZT thin film whose crystalline structure is tetragonal, in which the PbO excessive composition ratio Y is within a range of 0≦Y<0.5, and the Zr composition ratio X is within a range of 0.55≦X<1.
Patent Document 2 discloses a piezoelectric thin film having a thickness of 1 μm or more and 10 μm or less, a crystal grain size of 0.55 μm or less, and surface roughness of 1 μm or less at RMAX. The piezoelectric thin film is useful as a piezoelectric thin film for an ink-jet-type storage apparatus that requires a predetermined film thickness or more.